Self-grooming and rearing behavior. (A and B) Two mice were placed in a novel environment and grooming and rearing behaviors of each animal were scored. (A) Diesel exhaust particles (DEP)-treated (n = 16) animals spent significantly longer time self-grooming compared to controls (n = 24), (F1,18 = 8.282, P = 0.010). (B) Number of rearing episodes. There was a significant increase in number of rearing episodes in the DEP-treated animals compared to control animals, (F1,18 = 4.698, P = 0.04). (C and D) Single mouse was placed in test apparatus and self-grooming and rearing behaviors were scored. (C) No significant differences were observed between control (n = 24) and DEP-treated mice (n = 24) in the amount of time spent self-grooming (F1,46 = 0.084, P = 0.774). (D) Significant increase in rearing episodes was observed in DEP-treated mice compared to controls (F1,46 = 4.527, P = 0.039). Data are presented as mean ± SEM.